This invention relates to methane detection and more particularly to the direct electrochemical measurement of methane concentration in a gas. Direct electrochemical measurement is intended to refer to the measurement of an electrical signal generated by a chemical reaction.
Detection and measurement of methane in mines has long been important to the mining industry. In general, present methane-detecting instruments operate by measuring changes in the resistance of a heated platinum filament caused by catalytic oxidation of a flammable gas. In copending applications Ser. No. 585,699 filed Mar. 2, 1984 entitled Sensor Array for Toxic Gas Detection and Ser. No. 585,721 filed Mar. 2, 1984 entitled Combined Sensor Device for Detecting Toxic Gases, instruments are disclosed in which a filament is used to heat a gaseous component such as methane to form oxidation products. While the power levels for these instruments using hot filaments are not necessarily excessive, they are above desired values for the detection of methane in mines. Further, a second detecting device is often required to detect the oxidation products of methane.
Accordingly, one object of the invention is an instrument for the detection of methane. A second object of the invention is an instrument for the detection of methane which operates at a low power level. A third object of the invention is an instrument which operates at a low current level. Another object of the invention is an instrument responding to methane in the absence of air. An additional object of the invention is an instrument with a sensor capable of detecting methane by electrochemical oxidation at ambient temperatures. A further object of the invention is an instrument in which the electrochemical oxidation of methane results directly in an electrical signal representative of methane. These and other objects will become apparent from the following detailed description.